CAMRT Radiography Practice Exam

The QRS complex signifies the period of cardiac systole, which is the phase of the cardiac cycle when the heart muscle contracts and pumps blood out of the chambers.

During this time, the ventricles depolarize, leading to ventricular contraction. The QRS complex represents the electrical activity that initiates this contraction. The P wave, while important, indicates atrial depolarization and the onset of atrial contraction, which happens just before the QRS complex. The T wave follows the QRS complex and represents ventricular repolarization, occurring after the ventricles have contracted.

The R wave is a part of the QRS complex, specifically the peak of the wave, and by itself does not fully represent the entire process of systole. Thus, the QRS complex is the correct representation of cardiac systole, as it encapsulates the entire electrical event that leads to the mechanical contraction of the ventricles.